RCurl::postForm() -- how does one determine what the names are of each form element in an online html form?
2008/12/10 Tony Breyal <tony.breyal at googlemail.com>:
Dear R-Help,
I am looking into using the Open Calais web service (http://
sws.clearforest.com/calaisViewer/) for text mining purposes. I would
like to use R to post text into one of the forms on their website.
In package RCurl, there is a function called postForm(). This sounds
like it would do the job. Unfortunately the URL used in the example is
no longer valid (i have emailed the maintainer about this).
Question: How does one determine the name of the form elements to use?
is there an R function which will print out the names of these
elements perhaps?
[i am still learning, so please forgive me if i used the wrong
terminology.]
### Example from ?postForm ###
library(RCurl)
# Now looking at POST method for forms.
postForm("http://www.speakeasy.org/~cgires/perl_form.cgi",
"some_text" = "Duncan",
"choice" = "Ho",
"radbut" = "eep",
"box" = "box1, box2"
)
### Example ends ###
So in the above code, i believe the form elements are: "some_text",
"choice", "redbut" and "box". But how does one find out the names of
these form elements if one is not given them previously?
You need to look at the HTML source of the web page to work out what the form elements are called. However, in your case, it is not a simple form; rather the form is handled by a javascript function which uses Ajax to handle the request. Imitating the javascript, you may be able to post the data to http://sws.clearforest.com/calaisViewer//Bridge.asmx/BridgeMe with an element 'content' containing the (url-encoded) text, and an element 'type' = 'text/txt'. If that works it would return the result in an XML block.
I hope that the above made sense, and thank you kindly in advance for any help. Tony Breyal.
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